This.
It is totally up to you. Give what you feel you would like, depending upon how close you are to the couple and their family, and what you feel you can afford.
I find social snobs telling us what we should give, to be very offensive. (And I'm not one to be offended easily.)
While it is tradition to help a newlywed couple start their new life by giving a gift of some sort, whether cash or an actual gift, it is up to the giver to decide what they feel is appropriate. It has become common in our society that we seek help from the potential recipient, in selecting a gift that will be of value. After all, we don't want to give something that will only sit in the closet, or be returned. Unfortunately, this has led to an expectation on the part of recipients.
A gift, by definition, is something given without expectation of any type of payment in return. Thus the entire concept that a gift should be equal or greater in value than what is being spent on the guest, turns a gift into a payment for services rendered. When the family of a couple getting married plan a wedding, they are planning on a celebration of a wonderful event in the life of their son or daughter. They invite you as a guest to give joy to their family in the celebration, and to share in that joy. There should be no expectations for payment in return. If there are, that is very unfortunate.
So, make it a true gift, by giving from the heart. Give what you feel you would like them to have. And don't worry about what the social snobs say. If the recipient is offended, then that is very unfortunate. No friendship or family love should be based upon dollar amount.